The use of biomass as a renewable energy source has been investigated and proposed for many years. Three typical means of using biomass as an energy source include combustion, pyrolysis for the production of gaseous and liquid fuels, and fermentation for the production of ethanol. Sources of biomass can be plants which have certain specific characteristics and which are grown for this purpose, or waste materials from cultivated crops. Significant quantities and sources of biomass can be utilized for the production of energy.
The production of ethanol from biomass is known and is often referred to as “bio-ethanol”. The processes for the production of ethanol can be classified into two large categories: those which utilize sugar-containing raw materials—products of energetic cultivations (for example sweet sorghum) and those which utilize cellulosic raw materials originating from energetic cultivations (sorghum, cane, solid residue of sweet sorghum, etc.) as well as from other crop residues. In the first case sugars are directly fermented for the production of ethanol while in the second case a hydrolysis step or other processes are proceeded for the production of sugars which are then converted to ethanol via fermentation.
In regards to the use of sweet sorghum, it is known an energy source with continuing research directed to ethanol production from sorghum materials in the fermentation of extracted sugars. Another ways of using sorghum as a fuel product include the combustion of solid sorghum waste materials. The removal of sugar-containing fluids from sorghum produces considerable quantities of ligno-cellulosic residue, otherwise known as “bagasse”. To produce energy, raw sorghum bagasse can be burned as a fuel source.
However, no method is known which can produce ethanol in an energy self-sufficient on a year round basis. Thus, what is needed is a method of producing both ethanol derived from sugar-containing raw materials on a continuous and economical basis.